This invention relates to certain cyano-dienes and halopyridines and the processes for their preparation from a protected 1,3-dialdehyde and a cyano-diene.
The "sulfonylurea" herbicides are an extremely potent class of herbicides discovered within the last few years which generally consist of a sulfonylurea bridge, --SO.sub.2 NHCONH--, linking two aromatic or heteroaromatic rings. Research directed to methods for preparing sulfonylurea herbicides is continually producing new processes. The search for improved methods for more effectively preparing such compounds and intermediates required for preparing such compounds continues.
South African Patent Application 870,436 filed Jan. 21, 1987 discloses the use of compounds of Formula I in the preparation of pyridine sulfonylureas. ##STR1##
EP-A-237,292 published Sep. 16, 1987 discloses the use of compounds of the above Formula I in the preparation of pyridine sulfonylureas.
J. Org. Chem. 41, 2066 (1976) discloses the preparation of 2-bromonicotinic esters according to the following procedure. ##STR2##
J. Org. Chem. 38, 3436 (1974) discloses the preparation of nicotinamide from the 2-bromonicotinic esters according to the following procedure. ##STR3##
Japanese Patent 80-76,863, priority date Dec. 6, 1978, discloses the preparation of 2-chloro- nicotinic acids according to the following procedure. ##STR4##